1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a liquid crystal display device.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal panel and a backlight module. The operation principle of the liquid crystal panel is that liquid crystal molecules are interposed between two parallel pieces of glass and a plurality of vertical and horizontal fine electrical wires is arranged between the two pieces of glass, whereby the liquid crystal molecules are controlled to change direction by application of electricity in order to refract out light emitting from the backlight module for generating images. Since the liquid crystal panel itself does not emit light, light must be provided by the backlight module in order to normally display images. Thus, the backlight module is one of the key components of an LCD. The backlight module can be classified in two types, namely side-edge backlight module and direct backlight module, according to the position where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the back side of the liquid crystal panel to form a planar light source that directly provides lighting to the liquid crystal panel. The side-edge backlight module comprises a backlighting source of an LED light bar arranged at an edge of a backplane that is located rearward of one side of the liquid crystal panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face of the light guide plate and is projected out through a light emergence face of the light guide plate, after being reflected and diffused, to thereby form a planar light source for the liquid crystal panel.
Referring to FIG. 1, a liquid crystal display device generally comprises a backlight module 100, a mold frame 300 arranged on the backlight module 100, a liquid crystal display panel 500 arranged on the mold frame 300, and a front enclosure 700 arranged on the liquid crystal display panel 500. The backlight module 100 comprises a backplane 102, a light guide plate 104 received in the backplane 100, and a backlight source (not shown) mounted in the backplane 102. The backlight module 100 provides the liquid crystal display panel 500 with a planar light source of homogenous illumination. The mold frame 300 supports the liquid crystal display panel 500 and the front enclosure 700 retains the liquid crystal display panel 500 in the mold frame 300. The liquid crystal display panel 500 comprises a TFT (Thin-Film Transistor) substrate 502, a CF (Color Filter) substrate 504 that is set opposite to and laminated on the TFT substrate 502, and liquid crystal (not shown) interposed between the TFT substrate 502 and the CF substrate 504. The TFT substrate 502 is laminated on the CF substrate 504 in such a way that a stepped site 524 is formed at an edge of the TFT substrate 502. The stepped site 524 functions to receive a flexible circuit board (such as chip-on-flex, COF) 526 thereon for supplying a drive voltage to the liquid crystal display panel 500.
The front enclosure 700 is generally made of plastics for cost control purposes. The backplane 102 is generally made of metals, such as steel, to ensure strength of the backlight module 100. A liquid crystal display device of such a structure is susceptible to being not able to release static electricity generated by the flexible circuit board 526, resulting in the risk of electrostatics breakthrough of the flexible circuit board 526 and integrated circuits (not shown) and thus affecting the quality of the liquid crystal display device.
To cope with the problem, Chinese Patent Application (No. 201210068995.6) discloses a liquid crystal display device (as shown in FIG. 2), which comprises, sequentially from outer side to inner side, a front enclosure 100′, a mold frame 300′, and a backplane 500′ that are combined with each other. The front enclosure 100′ and the mold frame 300′ interpose therebetween a liquid crystal panel 700′. The front enclosure 100′ is made of an insulation material and a conductive film 102′ is arranged on a surface of the front enclosure 100′. The backplane 500′ is made of a conductive material and a conductor piece 502′ is provided between the conductive film 102′ and the backplane 500′, so that the conductive film 102′ is electrically connected, via the conductor piece 502′, to the backplane 500′. This arrangement uses the connection between the conductive film 102′ and the backplane 500′ that is made of a conductive material established with the conductor piece 502′ so that static electricity generated by a flexible circuit board (not shown) is discharged through the conductive film 102′ to the backplane 500′ to effectively protect the circuit board and integrated circuits from electrostatic breakthrough.
This solution effectively handles the issue of releasing static electricity but suffers the following drawbacks:
(1) The conductor piece that connects the front enclosure with the backplane lowers down the cost advantage of the plastics-made front enclosure.
(2) Bonding the conductor piece causes a waste of labor cost.
(3) The bonded conductor piece may get inadvertently detached and quality problems may result.